[1][2][3] Current designs of seismic metamaterials utilize configurations of boreholes,[4] trees [5][6] or proposed underground resonators to act as a large scale material.
These are the first experiments to verify that seismic metamaterials can be measured for frequencies below 100 Hz, where damage from Rayleigh waves is the most harmful to artificial structures.
[1][2] Giant polymer-made split ring resonators combined with other metamaterials are designed to couple at the seismic wavelength.
[8] The theory and ultimate development for the seismic metamaterial is based on coordinate transformations achieved when concealing a small cylindrical object with electromagnetic waves.
By understanding how permittivity and permeability control these components of wave propagation, applicable analogies can be used for other material interactions.
The computations then show that coordinate transformations can be applied to acoustic media when restricted to normal incidence in two dimensions.
Bulk modulus and mass density determine the spatial dimensions of the cloak, which can bend any incident wave around the center of the shell.
[3] In 2012, researchers held an experimental field-test near Grenoble (France), with the aim to highlight analogy with phononic crystals.
[10] This for the first time demonstrated that at the city scale, collective resonance of wind turbine structures can modify seismic waves propagating through it.
These new observations have implications for seismic hazard in a city where dense urban structures like tall buildings can strongly modify the wavefield.